Cut costs with an effective Poka Yoke culture

Poka Yoke was initially discussed in Japan over half a century ago by Shigeo Shingo who was employed as an engineer by Toyota.

Dr Shingo is also recognised as inventing and formalising zero quality control (Poka-Yoke methodologies to rectify potential manufacturing defects) + root cause examinations to avoid defects = zero defects quality control.

In Japanese, Poka Yoke means "mistake-proofing" Yokeru is literally "to avoid", whereas Poka translates as "inadvertent errors".  Poka Yoke devices are therefore employed to help avoid unintentional human or machine errors via behaviour-shaping decisions and constraints.

They help prevent errors by placing restrictions on how a particular process should be undertaken to help ensure that it's processed as intended, error free.  

It's illogical to expect that production staff can perform like machinery, with identical outcomes each time.  Just one minor interruption or distraction can result in work being processed incorrectly.  Badly designed processes needing close supervision will often contribute to unplanned problems.

Poka Yoke encourages designing or developing equipment, methodologies and procedures to make it very hard for anyone to make errors.  It’s based on the principle that everybody should work collectively to attain zero defects and that product quality begins with good design and quality should be embedded into manufacturing processes.

Conventional engineering methods have been designed to improve an operation’s efficiency by enabling staff and machinery to operate quickly. Poka Yoke doesn't contradict sound engineering methodologies and expands on those methodologies to incorporate ideas to help staff and equipment perform as intended.

Poka Yoke relies on inspection and by detecting defects before they have an effect on the assembly line.  Arithmetical quality inspection will eventually no longer be necessary, as there will be no defects to identify – resulting in "zero defects".

When a Poka Yoke is designed to help a machine operator to recognise defects before they take place, this is "prevention or prediction type" of Poka Yoke. Prevention-based mechanisms sense deviations from norms or intended outcome are about to occur, and then highlights the incident or ceases processing, depending on the deviation’s gravity, regularity or "knock-on" effects.

In several situations, it's not feasible or economically viable to avoid defects, especially where the capital outlay of the Poka Yoke device far exceeds the expense of prevention.  For these situations, defects are detected early on in the process preventing knock on effects and multiplying non-conformance expenses. This is called detection type Poka Yoke.

Embedding a Poka Yoke culture requires an organisation to assemble solid foundations in total quality management. Companies should learn to put their customers at the centre of their focus and ahead of everything else. They should encourage ownership for total quality and empower their staff to care about it.

They should embrace pre-inspection, self-examination, and post-inspection.  Poka Yoke needs up to date, real-time feedback and remedial action. These are the foundations of effective and valuable Poka Yoke systems. 

Errors often happen in manufacturing processes as a result of several factors or reasons.  But nearly all of them can be prevented if staff makes an effort to recognise or detect problems, define root causes, and then take appropriate remedial action.

The aim is to avoid, or at least, identify and eliminate defects, as soon as possible during a process. Poka Yoke’s simple application and other safeguards should also avoid errors from becoming costly or catastrophic.